He turned fifty-six years old.

Isoroku is my best friend and a very kind person.

Hydrogen is the most abundant element in the universe.

Hydrocarbons are fundamental components of organic chemistry.

Lithium hydride plays an important role in chemical reactions.

Hydrogen peroxide is often used for disinfecting wounds.

He was involved in the development of the hydrogen bomb.

Hydrogen sulphide is extremely toxic, and particularly at high concentrations, it is lethal to humans.

Hydrocarbon is a basic element of chemical reactions.

Arsine is a colorless, odorless, and highly toxic gas.